Image forming system

ABSTRACT

In an image forming system of the present invention, a master image forming apparatus determines, at the beginning of a joint copy job, whether or not a user stamp is registered at a slave image forming apparatus. If the user stamp is not registered at the slave image forming apparatus, the master image forming apparatus executes copying alone. Alternatively, the master image forming apparatus may send the user stamp to the slave image forming apparatus before the joint copy job. The system obviates erroneous copying in a joint copy mode and simply executes the joint copy mode even if the user stamp is not registered at the slave image forming apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of, and claims priorityto, Ser. No. 10/667,860, filed Sep. 23, 2003 (now U.S. Pat. No.6,766,118), which in turn is a continuation application of, and claimspriority to, Ser. No. 10/053,548, filed Jan. 24, 2002 (now U.S. Pat. No.6,643,473), and under 35 U.S.C. §119 from Japanese Application No.2001-017533, filed Jan. 25, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming system of the typeincluding a plurality of image scanners, word processors, personalcomputers or similar image signal outputting means and a plurality ofprinters or similar image forming means for forming images in accordancewith image signals output from the image signal outputting means.

2. Description of the Background Art

An image forming system of the type described has been proposed invarious forms for various purposes. Japanese, Patent Laid-OpenPublication No. 5-304575, for example, discloses an image forming systemincluding a plurality of digital copiers interconnected for the purposeof implementing high-speed copying. However, assume that a plurality ofimage forming apparatuses with an image storing capability are connectedtogether, and that a master image forming apparatus transfers an imagewhich it read to a slave image forming apparatus to cause it to printthe image in a joint operation mode. Then, if a user stamp registered bythe user is not available at the slave image forming apparatus, theslave image forming apparatus prints the image without combining theuser stamp with the image.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an image formingsystem in which a master image forming unit determines, at the beginningof a joint copy job, whether or not a user stamp is registered at aslave image forming apparatus and then performs copying alone if theanswer of the decision is negative, thereby obviating erroneous copying.

It is another object of the present invention to provide an imageforming system in which a master image forming apparatus determines, atthe beginning of a joint copy job, whether or not a user stamp isregistered at a slave image forming apparatus and then transfers, if theanswer of the decision is negative, the user stamp to the slave imageforming apparatus before the joint copy job, thereby effecting the jointcopy job with the user stamp while reducing the operator's work.

It is a further object of the present invention to provide an imageforming system in which a slave image forming apparatus deletes a userstamp after a joint copy job for thereby promoting the efficient use ofa memory.

In an image forming system of the present invention including aplurality of image forming apparatuses, the image forming apparatuseseach include a reading device for reading a document and a printingdevice for printing an image read by the reading device. A jointoperation device transfers the image read by the reading device toanother image forming apparatus and causes it to print the image. Ajoint copy mode selecting device commands the joint operation device toexecute a joint copy mode operation. A registering device allows theoperator to register a user stamp to be combined with the image in theevent of printing. A combining device combines the user stamp and image.A decision device determines whether or not the user stamp is registeredat the another image forming apparatus to which the joint operationdevice has transferred the image. When the joint copy mode operation isselected and if the user stamp is registered at the another imageforming apparatus, as determined by the decision device, the jointoperation device executes the joint copy mode operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription taken with the accompanying drawings in which:

FIG. 1 is a view showing an image forming apparatus included in an imageforming system embodying the present invention;

FIG. 2 is a plan view showing a specific configuration of an operationpanel mounted on the image forming apparatus;

FIG. 3 shows a specific picture to appear on an LC (Liquid Crystal)touch panel included in the operation panel;

FIG. 4 is a schematic block diagram showing a specific hardwareconfiguration of the image forming apparatus;

FIG. 5 is a schematic block diagram showing another specific hardwareconfiguration of the image forming apparatus;

FIG. 6 is a schematic block diagram showing two digital PPC (Plain PaperCopiers) connected together in the illustrative embodiment;

FIG. 7 shows serial data interchanged between the PPCs of FIG. 6 duringjoint mode operation;

FIG. 8 shows a specific picture to appear on the LC touch panel forallowing the operator to register or delete a user stamp;

FIG. 9 is a schematic block diagram showing a specific configuration ofan image processing section included in the image forming apparatus;

FIG. 10 is a block diagram schematically showing a specificconfiguration of a memory controller and an image memory included in theimage processing section;

FIG. 11 is a timing chart showing various signals to appear in the imageprocessing section;

FIG. 12 is a flowchart demonstrating a specific operation of theillustrative embodiment;

FIGS. 13 and 14 are flowcharts demonstrating another specific operationof the illustrative embodiment;

FIG. 15 shows a specific electronic sort mode operation available withthe illustrative embodiment; and

FIG. 16 is a block diagram showing a specific configuration of a CSS(Client Server System) included in the illustrative embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 of the drawings, an image forming apparatusembodying the present invention is shown. As shown, the image formingapparatus includes an ADF (Automatic Document Feeder) 1 including adocument tray 2. As shown in FIG. 2, a print start key 34 is positionedon an operation panel 30. When the print start key 34 is pressed, apickup roller 3 sequentially pays out documents stacked on the documenttray 2, the lowermost document first. A belt conveyor 4 conveys thedocument paid out from the document tray 2 to a preselected position ona glass platen 6.

After an image reading unit 50 has read image data out of the documentpositioned on the glass platen 6, the belt conveyor 4 and an outletroller pair 5 drive the document out of the ADF 1. When a document setsensor 7 senses the next document present on the document tray 2, thedocument is conveyed to the glass platen 6 in the same manner as theprevious document. A motor, not shown, drives the pickup roller 3, beltconveyor 4, and outlet roller pair 5.

A first, a second and a third tray 8, 9 and 10 each are loaded with astack of sheets of particular size. A first, a second and a thirdpick-up device 11, 12 and 13 pay out the sheets from the trays 8, 9 and10, respectively. A vertical conveying unit 14 conveys the sheet fedfrom any one of the trays 8 through 10 to a position where the sheetcontacts a photoconductive drum 15. An image writing unit 57 writes theimage data output from the reading unit 50 on the drum 15 with a laserbeam to thereby form a latent image. A developing unit 27 develops thelatent image with toner for thereby producing a corresponding tonerimage.

A belt 16 conveys the sheet at a speed equal to the rotation speed ofthe drum 15, so that the toner image is transferred from the drum 15 tothe sheet. A fixing unit 17 fixes the toner image on the sheet. A sheetdischarging unit 18 drives the sheet with the fixed toner image into afinisher 100 with an outlet roller pair not shown.

Usually, the finisher 100 selectively steers the incoming sheet towardan outlet roller pair 102 or toward a stapler, which will be describedhereinafter. Further, the finisher 100 is capable of shifting a switchplate 101 upward in order to discharge the sheet to a usual print tray104 via a roller pair 103. Alternatively, the finisher 101 may shift theswitch plate 101 downward in order to steer the sheet to a staple table108 via roller pairs 105 and 107.

Every time one sheet is driven out to the staple tray 108, a jogger 109positions the sheet. When sheets constituting a single set or copy arestacked on the staple tray 108, a stapler 106 staples the sheet. Thestapled set of sheets is let fall onto a tray 110 due to its own weight.

The usual print tray 104 is movable forward or backward in the directionperpendicular to the sheet surface of FIG. 1. More specifically, theprint tray 104 is movable back and forth document by document or set byset, which is sorted via an image memory, to thereby simply sort copiessequentially driven out to the tray 104.

In a duplex print mode for printing images on both sides of the sheet,the sheet fed from any one of the trays 8 through 10 and carrying animage on one side thereof is not driven out to the tray 104, but issteered to a duplex print unit 111 via a path selector 112.Subsequently, the duplex print unit 111 again feeds the one-sided sheettoward the drum 15 for forming another image on the other side of thesheet.

A main motor, not shown, drives the drum 15, belt conveyor 16, fixingunit 17, sheet discharging unit 18, and developing unit 27. The rotationof the main motor is transferred to the pickup devices 11 through 13 viarespective sheet feed clutches not shown. Also, the rotation of the mainmotor is transmitted to the vertical conveying unit 14 via anintermediate clutch not shown.

FIG. 2 shows a specific configuration of the operation panel 30 mountedon the image forming apparatus. As shown, an LC touch panel 31, numeralkeys 32, a clear/stop key 33, a mode clear key 35 and an initial set key38 are arranged on the operation panel 30 in addition to the print startkey 34. The LC touch panel 31 displays various function keys 37, anumber of sets or copies, a message showing the operator the status ofthe apparatus, and so forth.

FIG. 3 shows a specific picture appearing on the LC touch panel 31. Asshown, the picture includes various keys each being highlighted whentouched. When the operator who desires more detailed information on adesired function touches a key assigned to the function, the picture isreplaced with a picture displaying the details. In this manner, the LCtouch panel 31 uses a dot display and can therefore graphically displayoptimal information each time.

The LC touch panel 31 has a message area at its top left position, asviewed in FIG. 3. The message area displays various messages including“Ready to copy” and “Wait”. The number of copies set by the operatorappears at the right-hand side of the message area. An auto-density keyfor automatically controlling image density is positioned beneath thenumber of copies set. There are also shown on the LC touch panel 31 anauto-sheet select key for automatically selecting sheets to use, a sortkey for sorting copies set by set in order of page, a stack key forsorting copies page by page, a staple key for stapling sorted sheets setby set, a x1 key for setting x1 magnification, a magnification changekey for setting enlargement or reduction, a duplex print key, anerase/move key for setting, e.g., a margin mode, and a joint mode keyfor dividing a great number of prints into a plurality of groups via thenetwork of digital copiers.

Referring again to FIG. 1, the image reading unit 50 includes optics inaddition to the glass platen 6. The optics includes a lamp or lightsource 51, a first mirror 52, a lens 53, and a CCD (Charge CoupledDevice) array or similar image sensor 54. The lamp 51 and first mirror52 are mounted on a first carriage, not shown, while the second mirror55 and third mirror 56 are mounted on a second carriage not shown.

To read the document positioned on the glass platen 6, the firstcarriage and second carriages are mechanically moved at a relative speedratio of 2:1 so as not to vary the length of an optical path. A scannermotor, not shown, drives the optics. The image sensor 54 reads thedocument image and converts it to an electric signal. The lens 53 andimage sensor 54 are movable in the right-and left direction in FIG. 1 inaccordance with a desired magnification.

The image writing unit 57 includes a laser unit 58, a lens 59, and amirror 60. The laser unit 58 accommodates therein a laser diode or lightsource and a polygonal mirror, which is rotated by a motor, not shown,at high speed. A laser beam issuing from the laser unit 58 is deflectedby the polygonal mirror and then reflected by the mirror 60 to form abeam spot on the drum 15.

More specifically, the laser beam deflected by the polygonal mirrorscans the surface of the drum 15 perpendicularly to the direction ofrotation of the drum 15, i.e., in the main scanning direction. The laserbeam writes image data on the drum 15 line by line in accordance with animage signal output from a selector 64 (see FIG. 9), which is includedin an image processing section.

The electric image signal output from the image reading device, theelectric signal input to the image forming apparatus and synchronizingsignals will hereinafter be collectively referred to as an image orimage data for simplicity. The laser beam repeatedly scans the drum 15at a preselected period corresponding to the rotation speed of the drum15 and recording density, thereby forming a latent image on the drum 15.

A beam sensor, not shown, is located at a position adjoining one end ofthe drum 15 and to which the laser beam is to be incident. The beamsensor outputs a main scan synchronizing signal on sensing the laserbeam. The main scan synchronizing signal is used to control the timingfor starting image recording in the main scanning direction and togenerate a control signal for inputting and outputting an image signal,as will be described specifically later.

FIG. 9 shows a specific configuration of the previously mentioned imageprocessing section (image reading section and image writing section). Asshown, when the lamp 51 illuminates the document laid on the glassplaten, the resulting imagewise reflection is incident to the CCD imagesensor 54 via a lens not shown. The CCD image sensor 54 transforms theincident reflection to an electric signal. An AD(Analog-to-Digital)converter 61 converts the electric signal to acorresponding digital signal.

A shading corrector 62 corrects the shading of the digital image signaloutput from the AD converter 61. Shading is ascribable to the irregularlight distribution of the light source and the irregular sensitivity ofthe image sensor. An MTF (Modulation Transfer Function) and γ corrector63 executes MTF correction and γ correction with the image signal outputfrom the shading corrector 62. MTF correction obviates blur ascribableto the optics. A selector 64 selectively feeds the image signal to amagnification processor 71 or an image memory controller 65. Themagnification processor 71 enlarges or reduces the image signal inaccordance with a desired magnification. The image signal output fromthe magnification processor 71 is input to the image writing unit 57.The selector 64 and image memory controller 65 are capable ofinterchanging image signals with each other.

The image processing section is capable of selectively inputting oroutputting a plurality of different kinds of data, although not shown inFIG. 9 specifically. For example, the image processing section iscapable of dealing with image data output from a personal computer orsimilar data processing unit.

A CPU (Central Processing Unit) 68 controls the setting of the imagememory controller 65, image reading section 50, and image writingsection 57. A ROM (Read Only Memory) 69 and a RAM (Random Access Memory)70 respectively store a program and interim data to be dealt with by theCPU 68. Further, the CPU 68 is capable of writing and reading data outof an image memory 66.

Reference will be made to FIG. 11 for describing one page of imagesignal input to the selector 64. In FIG. 11, a frame gate signal /FGATEis representative of the valid period of one page of image data in thesubscanning direction. A line gate signal /LSYNC is the main scansynchronizing signal appearing line by line; the image signal becomesvalid when a preselected number of clock pulses appear after thepositive-going edge of the signal /LSYNC. The frame gate signal /FGATEand line gate signal /LSYNC are synchronous to a pixel clock VCLK. Onepixel data is input to the selector 64 for each period of the pixelclock VCLK. The image processor assigns a particular /FGATE, /LSYNC,/LGATE and VCLK generating mechanism to each of the input and output ofan image, so that the input and output of an image can be combined invarious ways.

FIG. 10 shows the memory controller 65 and image memory 66 in detail. Asshown, the memory controller 65 includes an input data selector 201, animage combiner 202, a primary compressor/expander 203, an output dataselector 204, and a secondary compressor/expander 205. The CPU 68 setsparticular control data in each of the above blocks 201 through 205. InFIG. 9, “address” and “data” are representative of image data; data andaddress input to the CPU 68 are not shown.

As shown in FIG. 10, the image memory 66 is made up of a primary and asecondary storage 206 and 207. The primary storage 206 allows data to bewritten and read thereoutof at high speed substantially in synchronismwith the transfer rate of the input image data. For this purpose, theprimary storage 206 is implemented by a DRAM (Dynamic RAM) or similarhigh-speed access memory.

The primary storage 206 has a plurality of areas each being assigned toimage data of particular size, so that image can be input and output atthe same time. More specifically, two sets of address and data linesconnect the primary storage 206 to an interface, which interfaces theprimary storage 206 to the memory controller 65, and are respectivelyassigned to reading and writing. This allows image data to be read outof, e.g., an area 2 when image data are being written to an area 1.

The secondary storage 207 is a large-capacity memory for storing imagedata in order to implement combination of input images or sorting ofimages. The primary and secondary storages 206 and 207 both may, ofcourse, be implemented by high-speed access memories, so that they candeal with image data in the same manner and can therefore be easilycontrolled. However, because a DRAM or similar high-speed access memoryis expensive, the secondary storage 207 is implemented by aninexpensive, large-capacity recording medium. The input and output ofdata from the secondary memory 207 is effected by way of the primarystorage 206.

With the image memory 66 having the above configuration, it is possibleto construct an image forming apparatus capable of inputting,outputting, storing, editing or otherwise processing a great amount ofimage data with a low cost, relatively simple configuration.

The operation of the memory controller 65 will be described hereinafter.How image data are written to the image memory 66 will be describedfirst. The input data selector 201 selects, among a plurality of datainput thereto, image data to be written to the primary storage 206. Theimage data selected by the selector 201 is input to the image combiner202 and combined with image data existing in the primary storage 206thereby. The primary compression/expander 203 compresses combined imagedata output from the image combiner 202 and writes the compressed imagedata in the primary storage 206. The image data written to the primarystorage 206 is further compressed by the secondary compressor/expander205 and then written to the secondary storage 207, if necessary.

How image data are read out of the image memory 66 will be describednext. Assume that an image to be output exists in the primary storage206. Then, the primary compressor/expander 203 expands the image dataread out of the primary storage 206. The output data selector 204selects the expanded data or the expanded data and input data combinedtogether and then outputs it.

The image combiner 202 executes the combination of image data present inthe primary storage 206 and input data (image data phase adjustingfunction) and the selection of the destination of combined data (imageoutputting, write-back to the primary storage 206, and simultaneousoutput to both of two destinations.

If an image to be output is absent in the primary storage 206, then thesecondary compressor/expander 205 expands the image data to be outputstored in the secondary storage 207 and then writes the expanded imagedata in the primary storage 206. This is also followed by the operationof the output data selector 204 described above.

FIGS. 4 and 5 respectively show a first and a second specific hardwareconfiguration of the image forming apparatus. As shown in FIG. 4, thefirst hardware configuration includes a memory unit 309 made up of acompression block 310, a DRAM block 311, and a DMA (Direct MemoryAccess) block 312. The DRAM block 311 stores the image signal outputfrom the image reading section 50 and can transfer image data storedtherein to the image writing section 57 in response to a request from asystem controller 306. The compression block 310 has an MH, MR, MMR orsimilar compressing function and compresses an image read for therebypromoting the efficient use of the memory (DRAM). In addition, thememory unit 309 rotates an image by changing addresses to read out ofthe image writing section 57 as well as direction.

A user limiting device 303 is connected to the system controller 306 forlimiting persons expected to use the apparatus. The user limiting device303 may be implemented as a coin rack, a key counter, a key card, aprepaid card or a code number by way of example. A human body sensor 304and a timepiece 307 are also connected to the system controller 306.

More specifically, in FIG. 4, the CPU 68 included in the systemcontroller 306 controls the image reading section 50, image writingsection 57, memory unit 309 and a CSS (Client Server System) 308 alone.The CSS is sometimes referred to as a remote diagnosis system or animage forming apparatus management system. On the other hand, in FIG. 5,the image reading section 50, image writing section 57 and memory unit309 each include a respective CPU; the system controller 306 sendscommands to such CPUs via control signal lines. In this manner, theillustrative embodiment is practicable with any desired system hardwareconfiguration.

FIG. 6 shows two digital PPCs connected together via a serial I/F andoperable in a joint mode. The serial I/F is exclusively assigned to thetransfer of image data. Of course, conventional RS232C or similar serialI/F, not shown, also connects the two PPCs for the interchange of setconditions, the number of documents and the number of prints as well asfor the response to a communication error.

FIG. 7 shows specific serial data transferred via the serial I/F. Asshown, the serial data consists of eight bits of data and one bit of ID(identification) bit, which is a data/communication error detectioncode. The serial data has therefore nine bits in total. The ID bit andcommunication error detection code are sent as “0” and “1”,respectively. When the sending PPC (master) transfers one page of imagedata to the receiving PPC (slave), it produces the sum of eight bits ofdata, calculates a communication error detection code such that the sumof the code is “0”, and then sends the calculated code at the end of onepage of data.

The receiving PPC produces the sum of received data. The receiving PCCthen determines that the data receipt is successful if the sum of thesum of the data and error detection code is “0” or determines that acommunication error has occurred if otherwise and reports it to thesending PPC.

FIG. 15 demonstrates a specific joint mode operation available with amaster machine and a slave machine. As shown, assume that in anelectronic sort mode available with a memory, a master machine 500 and aslave machine 600 cooperate to produce six sets or copies of prints.Then, the master machine 500 sequentially prints images read by thescanner while storing image data in the memory. On completing the firstset of prints, the master machine 500 reads the image data out of thememory to thereby produce the second sets of prints. The master machine500 then outputs the third set of prints in the same manner as it hasoutput the second sets of prints. The slave machine 600 writes the imagedata received from the master machine 500 in its memory and then startsoutputting the first set or volume of prints.

A procedure for registering a user stamp will be described hereinafter.FIG. 8 shows a specific picture to appear on the LC touch panel 31, FIG.2, for allowing a user stamp to be registered or deleted. Specifically,the operator selects a user stamp registration mode on the operationpanel 30, FIG. 2, selects a registered user number, sets a desireddocument on the glass platen 6, and then presses the print start button34. Then, the user stamp is written to and registered at the secondarystorage 207, FIG. 10, together with an image. The user stamp and imagedata are transferred from the secondary storage 207 to the imagecombiner 202 via the primary storage 206. As a result, the user stamp isprinted on a sheet together with the image data.

The master machine 500 determines whether or not the user stamp isregistered at the slave machine 600 via the serial I/F. Morespecifically, when the user stamp mode is selected on the master machine500, the master machine 500 determined whether or not the user stamp isregistered at the slave machine 600 via the serial I/F. If the userstamp is not registered at the slave machine 600, then master machine500 performs printing alone. Alternatively, the master machine 500 maysend the user stamp registered thereat to the slave machine 600 via theexclusive serial I/F at the time of transfer of image data, in whichcase the two machines 500 and 600 will operate in the joint mode. Afterthe printing operation, the user stamp registered at the slave machine600 is deleted.

A specific procedure to be executed by the master machine 500 will bedescribed with reference to FIG. 12. As shown, the master machine 500determines whether or not the joint mode is selected (step S100). If theanswer of the step S100 is positive (YES), then the master machine 500determines whether or not a user stamp is registered at the mastermachine 500 (step S110). If the answer of the step S110 is YES, then themaster machine 500 determines whether or not the user stamp isregistered at the slave machine 600 (step S120).

If the answer of the step S120 is YES or if the answer of the step S110is negative (NO), then the master machine 500 performs printing in thejoint mode together with the slave machine 600.

If the answer of the step S120 is NO or if the answer of the step S100is NO, then the master machine 500 performs printing in the usual copymode alone (step S130).

Another specific procedure available with the illustrative embodimentwill be described with reference to FIGS. 13 and 14. FIG. 13demonstrates the operation of the master machine 500. As shown, themaster machine 500 determines whether or not the joint mode is selected(step S200). If the answer of the step S200 is YES, then the mastermachine 500 determines whether or not a user stamp set mode is selected(step S210). If the answer of the step S210 is YES, then the mastermachine 500 determines whether or not a user stamp is registered at theslave machine 600 (step S220). If the answer of the step S220 is NO,then the master machine 500 transfers the user stamp to the slavemachine 600 (step S230) and then operates in the joint mode (step S240).

If the answer of the step S210 is NO of if the answer of the step S220is YES, then the master machine 500 performs printing in the joint modetogether with the slave machine 600 (step S240). On the other hand, ifthe answer of the step S200 is NO, then the master machine 500 operatesin the usual copy mode alone (step S250).

FIG. 14 show the operation of the slave machine 600 relating to theoperation of the master machine 500 described above. As shown, the slavemachine 600 determines whether or not the joint mode is selected (stepS300). If the answer of the step S300 is YES, the slave machine 600determines whether or not the user stamp set S310 is YES, then the slavemachine 600 determines whether or not the user stamp is registeredthereat (step S320). If the answer of the step S320 is NO, then theslave machine 600 receives the user stamp from the master machine 500(step S330) and then operates in the joint mode together with the mastermachine.

If the answer of the step S310 is NO or if the answer of the step S320is YES, then the slave machine 600 also operates in the joint modetogether with the master machine 500 (step S340).

After the joint mode operation, the slave machine 600 determines whetheror not the user stamp received from the master machine 500 has been used(step S350). If the answer of the step S350 is YES, then the slavemachine 600 deletes the received user stamp (step S360). On the otherhand, if the answer of the step S350 is NO, then the procedure ends.

If the joint mode is not selected (NO, step S300), then the slavemachine operates in the usual copy mode alone (step S370).

FIG. 16 shows a specific configuration of the CSS or remote diagnosissystem. As shown, a management unit 352 and PPCs 200 or similarapparatuses situated at the users'stations are connected by a publictelephone network 351. A CCU (Communication Control Unit) 350 issituated at each user's station for controlling communication of thePPCs 200 and the management unit 352. A telephone set or a facsimileapparatus 353 is connectable to the CCU 350 by using the existingsubscriber line. While a plurality of PPCs 200 are shown as beingconnected to the CCU 350, a single PPC may, of course, be connected tothe CCU 350. Further, the PPCs 200 connected to the same CCU 350 may beof the same type or of different types or may even be replaced withother apparatuses.

Assume that the maximum number of PPCs 200 connectable to the same CCU350 is five. Then, the CCU 350 and PPCs 200 are connected by multi-dropconnection based on the RS-485 standard. Control over communicationbetween the CCU 350 and the PPCs 200 uses the basic, data transfercontrol procedure. A data link is set up by a centralizedpolling/selecting system using the CCU 350 as a control station, so thatthe CCU 350 can communicate with any one of the PPC 200 connectedthereto. Each PPC 200 includes an address setting switch usable to set avalue particular to the PPC 200.

In summary, it will be seen that the present invention provides an imageforming system having the following various unprecedented advantages.Assume that a plurality of image forming apparatuses operate in a jointcopy mode by using a user stamp. Then, when the user stamp is notregistered at the destination or slave image forming apparatus, thejoint copy mode is automatically canceled to avoid erroneous copying.Alternatively, the master apparatus may execute the joint copy mode withthe slave apparatus after transferring the user stamp to the slaveapparatus. This makes it needless for the user stamp to be registered atthe slave apparatus before the joint mode operation, reducing theoperating time.

After the joint mode operation, the slave apparatus can delete the userstamp received from the master apparatus, promoting the effective use ofa memory. Moreover, the operator at the slave apparatus can determinewhether or not to effect the joint mode operation and can thereforeoutput prints to the operator's taste.

Various modifications will become possible for those skilled in the artafter receiving the teachings of the present disclosure withoutdeparting from the scope thereof.

1. A method of forming an image in a system including at least a firstimage forming apparatus and a second image forming apparatus,comprising: (a) reading an image on a document and outputting image dataaccording to said image on said document, step (a) being performed insaid first image forming apparatus; (b) storing additional data to beadded to said image data, step (b) being performed in said first imageforming apparatus; (c) printing an image according to said image dataand said additional data, step (c) being performed in said first imageforming apparatus; and (d) transferring said image data to said secondimage forming apparatus when said additional data is stored in saidsecond image forming apparatus, step (d) being performed in said firstimage forming apparatus.
 2. A method of forming an image in a systemincluding at least a first image forming apparatus and a second imageforming apparatus, comprising: (a) reading an image on a document andoutputting image data according to said image on said document, step (a)being performed in said first image forming apparatus; (b) storingadditional data configured to be added to said image data, step (b)being performed in said first image forming apparatus; (c) printing animage according to said image data and said additional data, step (c)being performed in said first image forming apparatus; (d) transferringsaid image data to said second image forming apparatus, step (d) beingperformed in said first image forming apparatus; and (e) preventing saidimage data from being transferred to said second image forming apparatuswhen said additional data is not stored in said second image formingapparatus.
 3. A method of forming an image in a system including atleast a first image forming apparatus and a second image formingapparatus, comprising: (a) reading an image on a document and outputtingfirst image data according to said image on said document, step (a)being performed in said first image forming apparatus; (b) storingsecond image data registered by an operator, step (b) being performed insaid first image forming apparatus; (c) printing an image according tothe first image data and the second image data, step (c) being performedin said first image forming apparatus; and (d) determining whether ornot said second image forming apparatus stores said second image data,step (d) being performed in said first image forming apparatus.
 4. Amethod of forming an image in a system including at least a first imageforming apparatus and a second image forming apparatus, comprising: (a)reading an image on a document and outputting first image data accordingto said image on said document, step (a) being performed in said firstimage forming apparatus; (b) storing second image data registered by anoperator, step (b) being performed in said first image formingapparatus; (c) printing an image according to the first image data andthe second image data, step (c) being performed in said first imageforming apparatus; and (d) transferring the first image data to saidsecond image forming apparatus when the second image data is stored insaid second image forming apparatus, step (d) being performed in saidfirst image forming apparatus.
 5. An image forming system including atleast a first image forming apparatus and a second image formingapparatus, comprising: receiving means for receiving image data, saidreceiving means being provided in said first image forming apparatus;storing means for storing additional data to be added to said imagedata, said storing means being provided in said first image formingapparatus; printing means for printing an image according to said imagedata received by said receiving means and said additional data stored insaid storing means, sand printing means being provided in said firstimage forming apparatus; and transferring means for transferring saidimage data to said second image forming apparatus when said additionaldata is stored in said second image forming apparatus, said transferringmeans being provided in said first image forming apparatus.
 6. An imageforming system including at least a first image forming apparatus and asecond image forming apparatus, comprising: receiving means forreceiving image data, said receiving means being provided in said firstimage forming apparatus; storing means for storing additional dataconfigured to be added to said image data, said storing means beingprovided in said first image forming apparatus; printing means forprinting an image according to said image data received by saidreceiving means and said additional data stored in said storing means,said printing means being provided in said first image formingapparatus; transferring means for transferring said image data to saidsecond image forming apparatus, said transferring means being providedin said first image forming apparatus; and preventing means forpreventing said transferring means from transferring said image data tosaid second image forming apparatus when said additional data is notstored in said second image forming apparatus.
 7. An image formingsystem including at least a first image forming apparatus and a secondimage forming apparatus, comprising: receiving means for receiving imagedata, said receiving means being provided in said first image formingapparatus; storing means for storing second image data registered by anoperator, said storing means being provided in said first image formingapparatus; printing means for printing an image according to the firstimage data output by said receiving means and the second image datastored in said storing means, said printing means being provided in saidfirst image forming apparatus; and determining means for determiningwhether or not said second image forming apparatus stores said secondimage data, said determining means being provided in said first imageforming apparatus.
 8. An image forming system including at least a firstimage forming apparatus and a second image forming apparatus,comprising: receiving means for receiving image data, said receivingmeans being provided in said first image forming apparatus; storingmeans for storing second image data registered by an operator, saidstoring means being provided in said first image forming apparatus;printing means for printing an image according to the first image dataoutput by said receiving means and the second image data stored in saidstoring means, said printing means being provided in said first imageforming apparatus; and transferring means for transferring the firstimage data to said second image forming apparatus when the second imagedata is stored in said second image forming apparatus, said transferringmeans being provided in said first image forming apparatus.
 9. An imageforming system including at least a first image forming apparatus and asecond image forming apparatus configured to communicate with the firstimage forming apparatus, comprising: receiving means for receiving imagedata, said receiving means provided in said first image formingapparatus; storing means for storing additional data to be added to saidimage data, said storing means being provided in said first imageforming apparatus; printing means for printing an image according tosaid image data received by said receiving means and said additionaldata stored in said storing means, said printing means being provided insaid first image forming apparatus; and determining means fordetermining whether or not said second image forming apparatus storessaid additional data, said determining means being provided in saidfirst image forming apparatus.
 10. A method of forming an image in asystem that includes at least a first image forming apparatus and asecond image forming apparatus configured to communicate with the firstimage forming apparatus, comprising: (a) receiving image data, step (a)being performed in said first image forming apparatus; (b) storingadditional data to be added to said image data, step (b) being performedin said first image forming apparatus; (c) printing an image accordingto said image data received in step (a) and said additional data storedin step (b), step (c) being performed in said first image formingapparatus; and (d) determining whether or not said second image formingapparatus stores said additional data, step (d) being performed in saidfirst image forming apparatus.